Industrial production is mainly from steam reforming of natural gas, oil reforming, or coal gasification. In 1766–1781, Henry Cavendish was the first to recognize that hydrogen gas was a discrete substance, and that it produces water when burned, the property for which it was later named: in Greek, hydrogen means "water-former". Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Because hydrogen is the only neutral atom for which the Schrödinger equation can be solved analytically, the study of its energetics and chemical bonding has played a key role in the development of quantum mechanics.
The H + cation is simply a proton (symbol p) but its behavior in aqueous solutions and in ionic compounds involves screening of its electric charge by nearby polar molecules or anions. In ionic compounds, hydrogen can take the form of a negative charge (i.e., anion) where it is known as a hydride, or as a positively charged (i.e., cation) species denoted by the symbol H +. Hydrogen plays a particularly important role in acid–base reactions because these reactions usually involve the exchange of protons between soluble molecules. Hydrogen is nonmetallic, except at extremely high pressures, and readily forms a single covalent bond with most nonmetallic elements, forming compounds such as water and nearly all organic compounds. The emergence of neutral hydrogen atoms throughout the universe occurred about 370,000 years later during the recombination epoch, when the plasma had cooled enough for electrons to remain bound to protons. In the early universe, the formation of protons, the nuclei of hydrogen, occurred during the first second after the Big Bang. For the most common isotope of hydrogen (symbol 1H) each atom has one proton, one electron, and no neutrons.
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Most of the hydrogen on Earth exists in molecular forms such as water and organic compounds. Stars such as the Sun are mainly composed of hydrogen in the plasma state. Hydrogen is the most abundant chemical substance in the universe, constituting roughly 75% of all normal matter. It is colorless, odorless, tasteless, non-toxic, and highly combustible. At standard conditions hydrogen is a gas of diatomic molecules having the formula H 2.
Hydrogen is the chemical element with the symbol H and atomic number 1. ‣ How many hydrogen isotopes are there? Main isotopes of hydrogen Isotope Abundance Half-life (t 1/2) Decay mode Product 1 H 99.98 % stable 2 H 0.02 % stable 3 H trace 12.(H 2) 20.271 K (−252.879 ☌, −423.182 ☏) ‣ Hydrogen vapor pressure Vapor pressure P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 15 20 Oxidation state: +1 ‣ What is the electronegativity value of hydrogen?Įlectronegativity: Pauling scale: 2.20 ‣ Hydrogen heat of fusion: (H 2) 0.117 kJ/mol ‣ Hydrogen heat of vaporization: (H 2) 0.904 kJ/mol ‣ Hydrogen molar heat capacity: (H 2) 28.836 J/(mol K) ‣ Hydrogen molar magnetic susceptibility: -3.98 × 10 -6 cm 3/mol (298 K) ‣ Speed of sound in hydrogen: 1310 m/s (gas, 27 ☌) ‣ What is the crystal structure of hydrogen?Ĭrystal structure: hexagonal ‣ Thermal conductivity of hydrogen: 0.1805 W/(m.K) ‣ Hydrogen CAS number: When liquid (at b.p): 0.07099 g/cm 3 ‣ Hydrogen magnetic ordering: diamagnetic ‣ Hydrogen natural occurrence: primordial ‣ What is the oxidation state of hydrogen? Phase (at r.t): gas ‣ What is hydrogen density? Ionization energies:1st: 1312.0 kJ/mol ‣ What phase of matter is hydrogen at room temperature? Melting point: (H 2) 13.99 K (-259.16 ☌, -434.49 ☏) ‣ What is hydrogen’s boiling point?īoiling point: (H 2) 20.271 K (-252.879 ☌, -423.182 ☏) ‣ Hydrogen critical point: 32.938 K, 1.2858 MPa ‣ Hydrogen triple point: 13.8033 K, 7.041 kPa ‣ How many electron shells does hydrogen have?Įlectrons per shell: 1 ‣ What is the ground state electron configuration for hydrogen?Įlectron configuration: 1s 1 ‣ What is hydrogen ionization energy? Period: 1 ‣ What is the covalent radius of hydrogen?Ĭovalent radius: 31±5 pm ‣ Hydrogen Van der Waals radius: 120 pm ‣ What is hydrogen melting point? Group: 1 (hydrogen and alkali metals) ‣ What is hydrogen’s period number? Standard atomic weight: conventional: 1.008 ‣ What block is hydrogen in the periodic table?īlock: s-block ‣ What group does hydrogen belong to? Symbol: H ‣ What is hydrogen’s atomic weight? ‣ What is hydrogen’s atomic number?Ītomic number (Z): 1 ‣ What is hydrogen symbol? Location: Hydrogen is found in the first column of the periodic table above the lithium element. Named by: Antoine Lavoisier (1783) ‣ Where is hydrogen located on the periodic table? – s block FAQs on Hydrogen Element Hydrogen ‣ What does hydrogen look like?Īppearance: colorless gas ‣ Who discovered hydrogen? When was hydrogen discovered?
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